1. Field of the Invention
The present invention relates to a recording device for recording on a recording medium by using a recording head.
2. Related Art
A conventional recording device includes a sensor for detecting temperature of a recording head or of a driving circuit that drives the recording head. When the temperature exceeds a predetermined temperature, the recording operation is either stopped or slowed down, thereby protecting the recording head and the driving circuit from overheating.
Japanese Patent Application Publication (Kokai) No. HEI-3-140248 discloses a diode serving as a sensor for detecting temperature of a heater, which heats up ink in an ink jet head, by utilizing its temperature characteristics of voltage drop in the forward direction. As shown in FIG. 3, the voltage drop in the forward direction is in inverse proportion to the temperature, and its relation curve TS forms a substantially straight line.
However, voltages output in response to temperature differ by a relatively large amount A among products. Therefore, when a voltage E1 is set for a voltage at, for example, 125xc2x0 C. so as to stop recording operations at 125xc2x0 C., the voltage E1 may be output before the temperature reaches 125xc2x0 C., or may not be output even when the temperature exceeds 125xc2x0 C. When the voltage E1 is output before reaching 125xc2x0 C., the recording operation will be unnecessarily stopped. For example, even when the recording device has capability to continuously perform the recording operation on a large number of pages, the recording operation will be stopped when the operation is performed on only a few pages. On the other hand, when the temperature exceeds 125xc2x0 C. without the voltage E1 being output, the driving circuit may be damaged due to overheating.
It is an objective of the present invention to overcome the above problems, and also to provide a recording device capable of accurately and reliably controlling its operation based on temperature regardless of unevenness in temperature characteristics of voltage drop in the forward direction.
In order to achieve the above and other objectives, there is provided a recording device including a recording element, a drive circuit, a first sensor, a memory, a calculation unit, and a control circuit. The drive circuit drives the recording element. The first sensor outputs a signal corresponding to a temperature around at least one of the recording element and the drive circuit. The memory stores a first data corresponding to a first temperature. The first data relates to a first signal output by the first sensor at the first temperature. The calculation unit obtains a data relating to the signal in accordance with the first data stored in the memory. The control circuit regulates the drive circuit to drive the recording element when the data obtained by the calculation unit corresponds to a predetermined second temperature higher than the first temperature.
There is also provided a recording device including a recording element, a driving circuit, a sensor, a calculation unit, and a control circuit. The driving circuit drives the recording element. The sensor outputs a voltage corresponding to a temperature around at least one of the recording element and the driving circuit. The sensor has temperature characteristics of voltage drop in forward direction. The memory stores a first data corresponding to a first temperature. The first data relating to both a coefficient of a relation curve of the temperature characteristics and a first voltage output by the sensor at the first temperature. The calculation unit obtains a second data relating to the voltage in accordance with the first data stored in the memory.